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README: update for libgsmfr2+libgsmefr+libtwamr set
author Mychaela Falconia <falcon@freecalypso.org>
date Fri, 10 May 2024 02:36:34 +0000
parents 1b8cb3490d48
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450:16bc3036cc84 451:614ae8dc6807
2 =========================================================== 2 ===========================================================
3 3
4 Themyscira Wireless, a technical initiative of the Women's Republic of 4 Themyscira Wireless, a technical initiative of the Women's Republic of
5 Themyscira, is proud to present this package of GSM codec libraries and 5 Themyscira, is proud to present this package of GSM codec libraries and
6 associated command line test and development utilities. The present package 6 associated command line test and development utilities. The present package
7 provides two linkable C libraries, intended to be usable by any application 7 provides the following linkable C libraries, intended to be usable by any
8 that needs GSM codec functionality: 8 application that needs GSM codec functionality:
9 9
10 libgsmefr An implementation of EFR codec in the same spirit as classic 10 libgsmfr2 This library implements the original GSM-FR codec, consisting
11 libgsm, i.e., like libgsm, but for EFR instead of 06.10. It is 11 of not only the basic transcoding functions of GSM 06.10, but
12 based on the reference code from ETSI. 12 also all Rx DTX handler functions that are required for a speech
13 decoder receiving a stream of frames from a radio interface,
14 either MS or network side. This library is a replacement for
15 classic libgsm, providing proper reset logic, homing functions
16 and the Rx DTX handler block.
13 17
14 libgsmfrp An Rx DTX handler preprocessor to be invoked prior to 18 libgsmefr This library implements GSM-EFR codec, based on the reference
15 gsm_decode() from classic libgsm, implementing GSM 06.11, 06.12 19 code from ETSI (GSM 06.53). The bit-exact version of GSM-EFR
16 and 06.31 functionality in the Rx direction. 20 implemented here is the original one, not the AMR-EFR hybrid
21 that was made into a permissible implementation option after
22 the development of AMR.
17 23
18 These two libraries are intended primarily for use as part of GSM network 24 libtwamr This library implements 3GPP AMR-NB codec, based on the official
19 deployment, i.e., as part of the necessary speech transcoder implementation in 25 reference code (TS 26.073). Both VAD versions are included,
20 whichever network-side server process acts as the voice gateway to PSTN or 26 selected by the user application at run time, and I/O functions
21 other networks. However, they can also be used as part of development and 27 are provided for both 3GPP test sequence format and the more
22 testing on the mobile side of GSM: for example, to decode TCH downlink bits and 28 practical format of IETF RFC 4867. This library can also be
23 voice memo recordings read out of FreeCalypso GSM MS devices, or to implement 29 used to implement AMR-EFR hybrid operation if no DTX is needed
24 your own lab-oriented GSM MS on top of some other PHY. 30 in the encoder and if the input to the decoder contains no SID
31 frames.
25 32
26 Each of these two Themyscira libraries (libgsmefr and libgsmfrp) is free- 33 The only GSM codec for which no implementation library is currently provided is
27 standing and independent of the other. libgsmfrp makes use of <gsm.h> header 34 GSM-HR, also known as HRv1. Librification of HRv1 reference code from ETSI is
28 file from libgsm (for gsm_byte and gsm_frame defined types) and requires this 35 a planned work item for future development.
29 header file in order to compile; libgsmefr has zero dependencies nominally but 36
30 will often be used together with libgsm and libgsmfrp. 37 The libraries provided here are intended for two primary purposes:
38
39 1) They are used as part of Themyscira Wireless MGW (media gateway)
40 implementation, providing the necessary speech transcoder between a GSM
41 network and G.711-based PSTN.
42
43 2) They are useful in many varied study and exploration workings, as part of
44 experiments where it becomes necessary to model, simulate or replicate
45 bit-exact operation of someone else's network element.
46
47 Each of our Themyscira core libraries is free-standing and independent of the
48 others. The dependency on classic libgsm (by way of <gsm.h> header file) that
49 existed in previous versions of Themyscira gsm-codec-lib suite has been
50 eliminated; the present version has zero dependencies.
31 51
32 Included command line utilities 52 Included command line utilities
33 =============================== 53 ===============================
34 54
35 In addition to the two main libraries, the present package includes a number of 55 In addition to the set of core libraries, the present package includes a number
36 command line utilities, falling into the following groups: 56 of command line utilities, falling into the following groups:
37 57
38 * Some utilities specifically exercise and test the two core libraries; 58 * Some utilities specifically exercise and test our core libraries;
39 59
40 * Some utilities are not specifically for library testing but make use of 60 * Some utilities are not specifically for library testing but make use of
41 our libraries; 61 these libraries;
42 62
43 * Some utilities are included because they implement some closely related and 63 * Some utilities are included because they implement some closely related and
44 relevant debug and development functionality, even though they don't link 64 relevant debug and development functionality, even though they don't link
45 with either libgsmefr or libgsmfrp. 65 with any of the included core libraries.
46 66
47 Please see the included documentation in the doc subdirectory. 67 Please see the included documentation in the doc subdirectory.